Gems
Natural gems we can meet could be of organic and non organic origin. Non organic gem stones are of three types – minerals (most common type), rocks (like lapis lazuli) or petrified materials (after simple cut and polishing can be used in jewelry). Among the organic there are such gems as fossilized tree resin amber, corals, pearls and a form of coal called jet. In nature we can also meet some gems that are very fragile or soft to be put in jewelry, so they usually are exhibited in the museums or auctions. The fine example of such gems is single-crystal rhodochrosite.
Along with gem stones that have natural origin started to appear so called synthetic gems. These are the stones created in the laboratory conditions. Usually these gems are created in order to imitate other gems. For example synthetic diamond imitation is cubic zirconium. The imitations may copy color and look of a gem but are a bit different in their physical and chemical characteristics. All of them, even diamonds, rubies, sapphires and emeralds can be produced in laboratories. Artificial sapphires and rubies are quite common and they cost much less than natural stones. However quality synthetic diamonds are still too costly to manufacture.
The appearance or look are the most important gemstone attributes. And they are mostly prized and valued for their perfection and beauty.
Their beauty must also be able to stand the test of time; if a gemstone is scratched or crumbled, it loses its value instantly. Characteristics using which gems are graded are the following: color, inclusions, shape, the gem’s rarity and optical phenomena. That is why diamonds are highly valued as gems. They are hardest substance ever known, are able to reflect light with fire, sparkle and are met rarely in nature.
There are occasions when the gems should be treated in order to increase their value. Treatment can artificially enhance gem’s color, durability or clarity. Among such treatments most common are irradiation, heat treatment and staining. Irradiation treatment process was invented for gems color changes. But there are great drawbacks in doing diamonds green or rose quartz brown. The irradiation changes are not permanent and what is more the gem stones may become radio active.
Heat treatment is the oldest treatment known. Even in ancient times heat treated quartz was manufactured to obtain topaz. Also brownish zircon may become bright blue or even colorless, yellow topaz may become pink one, slightly colored chalcedony may become carnelian red, and some amethysts or rubies are more evenly colored. As for staining- jewelers often stain agate, turquoise and jasper to imitate opals and Lapis Lazuli gems.
Searching for good gems try to choose those that were calibrated. What are calibrated gems you ask? Calibrated are called gem stones that has standard dimensions (size is measured in mm) and that are cut to fit ready made jewelry. That means that a lot of gems are cut to compatible dimensions that are known as calibrated sizes. These gemstones fit into a variety of different settings. So you can always ask your jeweler to help you and select the best combination for you.
